Certain clinical and morphologic observations are described in 27 patients with severe isolated angina pectoris of either the stable (five patients) or the unstable form (22 patients). During life none had had clinical evidence of acute myocardial infarction or congestive cardiac failure. At necropsy, each had diffuse, extensive coronary atherosclerosis with severe luminal narrowing. Despite the severe coronary narrowing, there was little myocardial damage.